1. Field of the Invention
The present invention relates to a starter for starting an engine and, more particularly to a starter having a water drainage hole.
2. Description of Related Art:
In one type of a conventional starter such as disclosed in Japanese Laid-open Patent Publication No. 8-61196, the starter comprises a pinion gear, a helical spline of which mates the helical spline formed on the periphery of an output shaft, and a rotation restriction member restricting the rotation of the pinion gear. In order to engage the pinion gear with the ring gear of an engine, when the armature is rotated, the rotation restriction member is operated by the attraction force of an electromagnetic switch to restrict the rotation of the pinion gear and move the pinion gear axially by a thrust generated on the helical spline.
This starter allows the attraction force of the electromagnetic switch to be smaller than that of the other type of starter which engages the pinion gear with the ring gear by pressing the pinion gear axially to the ring gear by the attraction force of the electromagnetic switch. Thus, the starter according to the patent publication is effective for reducing the size of the electromagnetic switch in size, thus allowing the electromagnetic switch to be positioned at the rear of a starting motor. Consequently, the starter can be manufactured compactly and efficiently accommodated within the clutch housing of the engine.
However, in this type of starter in which the rotation of the pinion gear is restricted, water which has penetrated into the clutch housing tends to flow into the starter from the open portion of a front case and stays at the lower part of the front case. Consequently, there is a possibility that the connection member connecting the electromagnetic switch and the rotation restriction member with each other makes an unpreferable sliding contact owing to rust caused by the water which has collected in the front case.